本文選題：燃煤鍋爐　切入點：神經(jīng)網(wǎng)絡(luò)　出處：《南昌大學(xué)》2015年碩士論文

【摘要】：隨著經(jīng)濟的發(fā)展,環(huán)境污染愈加嚴(yán)重,目前燃煤發(fā)電機組作為我國的主要發(fā)電設(shè)備的狀況不會短期內(nèi)改變,而2011年版《火電廠大氣污染排放標(biāo)準(zhǔn)》的出臺,對燃煤電站的高效低污染運行提出了更加嚴(yán)苛的要求。近年來我國燃煤機組大都加裝的脫硝設(shè)備,使NOx排放值低于國家標(biāo)準(zhǔn),這樣必然影響燃煤電站的經(jīng)濟性,因此鍋爐的高效低污染燃燒優(yōu)化運行的研究具有重要意義。對某660MW燃煤電站鍋爐進行混煤摻燒熱態(tài)試驗,選取該電廠經(jīng)常運行的三個工況,按照實驗室得出的配煤方案進行效率及污染排放物試驗。試驗結(jié)果表明,在660MW負荷下,采用方案二的上煤方式,鍋爐在變氧量測試中氧量為2.5%時鍋爐的熱效率最高,為93.57%;600MW負荷下,采用方案四的上煤方式,鍋爐在變氧量測試中氧量為2.0%時鍋爐的熱效率最高,為93.68%;550MW負荷下采用方案六的上煤方式,鍋爐在變氧量測試中氧量為2.5%時鍋爐的熱效率最高,為93.60%。鍋爐NOx的排放濃度隨著氧量的增加而升高,因此在運行過程中應(yīng)保證氧量穩(wěn)定在最佳氧量值,使鍋爐高效低污染運行。在熱態(tài)試驗的基礎(chǔ)上應(yīng)用BP神經(jīng)網(wǎng)絡(luò)建立鍋爐排放特性模型,得到了較好的結(jié)果。網(wǎng)絡(luò)能夠很好得映射輸入與輸出之間的關(guān)系,NOx排放模型的平均相對誤差為0.73%,其中最大相對誤差出現(xiàn)在樣本9處,最大相對誤差為4.6%。三個測試樣本的相對誤差分別為0.46%,0.59%和2.34%,平均相對誤差為1.13%。鍋爐效率的網(wǎng)絡(luò)的平均誤差為0.13%,平均相對誤差為0.4%。結(jié)合遺傳算法對所建立的網(wǎng)絡(luò)模型進行優(yōu)化,優(yōu)化后的模型精確度和泛化能力有所提高。優(yōu)化后的網(wǎng)絡(luò)平均誤差為0.18%,較優(yōu)化前的0.73%大大降低,校驗樣本的相對誤差分別為0.39%、0.51%、0.8%,平均誤差為0.57%。優(yōu)化結(jié)果表明,遺傳算法對BP網(wǎng)絡(luò)訓(xùn)練的初始權(quán)值的優(yōu)化是有效的,可以提高網(wǎng)絡(luò)的精確度和泛化能力。在網(wǎng)絡(luò)建立的基礎(chǔ)上,對鍋爐的NOx排放進行優(yōu)化,優(yōu)化前的習(xí)慣工況下NOx濃度為458.4mg/m3,采用優(yōu)化后的運行方式NOx濃度降低為329.7mg/m3,降低了28%,效果明顯。優(yōu)化后的操作運行方式能夠體現(xiàn)鍋爐燃燒的燃料分級與配風(fēng)分級,從而抑制NOx的生成。
[Abstract]:With the development of economy, environmental pollution is becoming more and more serious. The status of coal-fired generating units as the main power generation equipment in China will not change in the short term. However, the 2011 edition of the Standard of Atmospheric pollution emissions from Thermal Power plants has been issued. More stringent requirements have been put forward for the operation of coal-fired power stations with high efficiency and low pollution. In recent years, most coal-fired units in China have installed denitrification equipment, which makes the NOx emission value lower than the national standard, which will inevitably affect the economy of coal-fired power stations. Therefore, it is of great significance to study the optimal operation of boiler combustion with high efficiency and low pollution. For a 660MW coal-fired power plant boiler, the heat state of mixed coal combustion is tested, and the three operating conditions of the power plant are selected. According to the coal blending scheme obtained in the laboratory, the efficiency and pollution emissions are tested. The results show that under the 660MW load, the boiler has the highest thermal efficiency when the oxygen quantity of the boiler is 2.5 in the test of the variable oxygen quantity, and the coal feeding mode of the second scheme is adopted. Under the load of 93.57MW and 600MW, the boiler has the highest thermal efficiency when the oxygen quantity of the boiler is 2.0 in the test of the variable oxygen quantity, and the coal feeding mode of scheme six is adopted under the load of 93.68MW / 550MW. The boiler has the highest thermal efficiency of 93.60 when the oxygen quantity is 2.5 in the variable oxygen quantity test. The NOx emission concentration of the boiler increases with the increase of oxygen quantity, so the oxygen quantity should be stabilized at the optimum oxygen value during the operation. The boiler is operated efficiently and low pollution. On the basis of thermal test, BP neural network is used to establish the boiler emission characteristic model. The network can well map the relation between input and output. The average relative error of NOx emission model is 0.73, and the maximum relative error appears in 9 samples. The maximum relative error is 4.6. The relative error of the three test samples is 0.46% and 2.34%, the average relative error is 1.130.The average error of boiler efficiency network is 0.13 and the average relative error is 0.4. The accuracy and generalization ability of the optimized model are improved. The average error of the optimized network is 0.18, which is much lower than the 0.73% before the optimization. The relative error of the calibration sample is 0.390.51 and the average error is 0.57. Genetic algorithm is effective to optimize the initial weights of BP network training, which can improve the accuracy and generalization ability of the network. Based on the establishment of the network, the NOx emission of boiler is optimized. The concentration of NOx is 458.4 mg / m ~ (3) under normal working conditions before optimization, and the concentration of NOx is reduced to 329.7 mg / m ~ (3) by using the optimized operation mode, which reduces 28mg / m ~ (3), and the effect is obvious. The optimized operation mode can reflect the fuel classification and air distribution classification of boiler combustion. Thus, the formation of NOx was inhibited.
【學(xué)位授予單位】：南昌大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X773;TP18

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